to continue (a little) the old goto debate,
one of the uses of goto is to get to the end of a block from an if without
writing a 1000 nexted if else's ........

I'd like to be able to write
    done:{
        ....
        if (...) {
            if ( ... ) { break done; }
        }
    }

instead of writing
    done:do{
        ....
        if (...) {
            if ( ... ) { break done; }
        }
    } while( false );

Named break and goto are effectively the same thing, right?  Labels attach to the beginning or end of their block?  I'd rather them attach exactly at the point of flow where the label is encountered, so you can put the label either before or after a block.  Simpler than trying to identify the labels with a loop or block.

Maybe if we removed the goto keyword while in the meantime extending the power of the named break to effectively replace it... it would satiate the whiners, a little bit.  ;)

Sean

"Mike Wynn" <mike.wynn@l8night.co.uk> wrote in message news:bi1t45$227t$1@digitaldaemon.com...
> to continue (a little) the old goto debate,
> one of the uses of goto is to get to the end of a block from an if without
> writing a 1000 nexted if else's ........
>
> I'd like to be able to write
>     done:{
>         ....
>         if (...) {
>             if ( ... ) { break done; }
>         }
>     }
>
> instead of writing
>     done:do{
>         ....
>         if (...) {
>             if ( ... ) { break done; }
>         }
>     } while( false );

"Sean L. Palmer" <palmer.sean@verizon.net> a écrit dans le message de news:bi1uqh$24u2$1@digitaldaemon.com...
> Named break and goto are effectively the same thing, right?  Labels attach to the beginning or end of their block?  I'd rather them attach exactly at the point of flow where the label is encountered, so you can put the label either before or after a block.  Simpler than trying to identify the
labels
> with a loop or block.
>
> Maybe if we removed the goto keyword while in the meantime extending the power of the named break to effectively replace it... it would satiate the whiners, a little bit.  ;)
>
> Sean
>
> "Mike Wynn" <mike.wynn@l8night.co.uk> wrote in message news:bi1t45$227t$1@digitaldaemon.com...
> > to continue (a little) the old goto debate,
> > one of the uses of goto is to get to the end of a block from an if
without
> > writing a 1000 nexted if else's ........
> >
> > I'd like to be able to write
> >     done:{
> >         ....
> >         if (...) {
> >             if ( ... ) { break done; }
> >         }
> >     }
> >
> > instead of writing
> >     done:do{
> >         ....
> >         if (...) {
> >             if ( ... ) { break done; }
> >         }
> >     } while( false );
>
>

I think that labelled break and continue should only allows a target that instruction that already support break or continue.

If we need more power (i.e. arbitrary target) we can (and
should uses goto).

That way, break would always mean that we break a loop
(or a switch) and continue that we continue a loop (or maybe
a case if continue is used for fall-through).

So for example, it would not be possible to do an infinite loop like above using break...

"Mike Wynn" <mike.wynn@l8night.co.uk> wrote in message news:bi1t45$227t$1@digitaldaemon.com...
> to continue (a little) the old goto debate,
> one of the uses of goto is to get to the end of a block from an if without
> writing a 1000 nexted if else's ........
>
> I'd like to be able to write
>     done:{
>         ....
>         if (...) {
>             if ( ... ) { break done; }
>         }
>     }
>
> instead of writing
>     done:do{
>         ....
>         if (...) {
>             if ( ... ) { break done; }
>         }
>     } while( false );
>

I think it'd be better called "break from block to label's scope". If you
can do it for any statement, what about  mylabel: break;  is that statement
just skipped or does break break out of something else?
This sounds like a good idea, although it doesn't exactly replace goto. I
tend to think those loop tricks are more of a hack than using goto, this
seems like a pretty good compromise.

"Philippe Mori" <philippe_mori@hotmail.com> wrote in message news:bi2hn3$2vd3$1@digitaldaemon.com...
>
> "Sean L. Palmer" <palmer.sean@verizon.net> a écrit dans le message de news:bi1uqh$24u2$1@digitaldaemon.com...
> > Named break and goto are effectively the same thing, right?  Labels
attach
> > to the beginning or end of their block?  I'd rather them attach exactly
at
> > the point of flow where the label is encountered, so you can put the
label
> > either before or after a block.  Simpler than trying to identify the
> labels
> > with a loop or block.
> >
> > Maybe if we removed the goto keyword while in the meantime extending the power of the named break to effectively replace it... it would satiate
the
> > whiners, a little bit.  ;)
> >
> > Sean
> >
> > "Mike Wynn" <mike.wynn@l8night.co.uk> wrote in message news:bi1t45$227t$1@digitaldaemon.com...
> > > to continue (a little) the old goto debate,
> > > one of the uses of goto is to get to the end of a block from an if
> without
> > > writing a 1000 nexted if else's ........
> > >
> > > I'd like to be able to write
> > >     done:{
> > >         ....
> > >         if (...) {
> > >             if ( ... ) { break done; }
> > >         }
> > >     }
> > >
> > > instead of writing
> > >     done:do{
> > >         ....
> > >         if (...) {
> > >             if ( ... ) { break done; }
> > >         }
> > >     } while( false );
> >
> >
> So for example, it would not be possible to do an infinite loop like above using break...

read the code .... `} while( false);`
its only every run once, no infinite loop, its just a do..while loop to
allow break to break from it
instead of goto to the statement just after the loop end (break breaks from
loop it does not goto label)

"Mike Wynn" <mike.wynn@l8night.co.uk> a écrit dans le message de news:bi3ngf$1nn4$2@digitaldaemon.com...
>
> "Philippe Mori" <philippe_mori@hotmail.com> wrote in message news:bi2hn3$2vd3$1@digitaldaemon.com...
> >
> > "Sean L. Palmer" <palmer.sean@verizon.net> a écrit dans le message de news:bi1uqh$24u2$1@digitaldaemon.com...
> > > Named break and goto are effectively the same thing, right?  Labels
> attach
> > > to the beginning or end of their block?  I'd rather them attach
exactly
> at
> > > the point of flow where the label is encountered, so you can put the
> label
> > > either before or after a block.  Simpler than trying to identify the
> > labels
> > > with a loop or block.
> > >
> > > Maybe if we removed the goto keyword while in the meantime extending
the
> > > power of the named break to effectively replace it... it would satiate
> the
> > > whiners, a little bit.  ;)
> > >
> > > Sean
> > >
> > > "Mike Wynn" <mike.wynn@l8night.co.uk> wrote in message news:bi1t45$227t$1@digitaldaemon.com...
> > > > to continue (a little) the old goto debate,
> > > > one of the uses of goto is to get to the end of a block from an if
> > without
> > > > writing a 1000 nexted if else's ........
> > > >
> > > > I'd like to be able to write
> > > >     done:{
> > > >         ....
> > > >         if (...) {
> > > >             if ( ... ) { break done; }
> > > >         }
> > > >     }
> > > >
> > > > instead of writing
> > > >     done:do{
> > > >         ....
> > > >         if (...) {
> > > >             if ( ... ) { break done; }
> > > >         }
> > > >     } while( false );
> > >
> > >
> > So for example, it would not be possible to do an infinite loop like above using break...
>
> read the code .... `} while( false);`
> its only every run once, no infinite loop, its just a do..while loop to
> allow break to break from it
> instead of goto to the statement just after the loop end (break breaks
from
> loop it does not goto label)
>
>
>

The original code has a while but not the suggested remplacement... but not I see that break would mean goto after labelled instruction while continue would be generally equivalent to goto except that continue will not do the initialisation part or a for instruction.

I haven't noticed before that the meaning was different that with a goto in such a case... so effectivelly they could be usefull on occasion as they would better document the code...

void f(int a)
{
    ext_loop : for (int i = 0; i < 10; ++i)
    {
        while (1)
        {
            if (a == 0) break ext_loop;    // 1
            if (a == 1) goto ext_loop;    // 2
            if (a == 2) continue ext_loop;    // 3
        }
    }
}

would essentially be equivalent to :

void f(int a)
{
    {
        ext_loop_a :
        int i = 0;

        ext_loop_b :
        for ( ; i < 10; ++i)
        {
            while (1)
            {
                if (a == 0) goto ext_loop_c;    // 1
                if (a == 1) goto ext_loop_a;    // 2
                if (a == 2) goto ext_loop_b;    // 3
            }
        }
        ext_loop_c:
    }
}

I know, f will loop forever if a is 2...

That's certainly interesting!

Sean

"Philippe Mori" <philippe_mori@hotmail.com> wrote in message news:bi4175$2662$1@digitaldaemon.com...
> The original code has a while but not the suggested remplacement... but not I see that break would mean goto after labelled instruction while continue would be generally equivalent to goto except that continue will not do the initialisation part or a for instruction.
>
> I haven't noticed before that the meaning was different that with a goto in such a case... so effectivelly they could be usefull on occasion as they would better document the code...
>
> void f(int a)
> {
>     ext_loop : for (int i = 0; i < 10; ++i)
>     {
>         while (1)
>         {
>             if (a == 0) break ext_loop;    // 1
>             if (a == 1) goto ext_loop;    // 2
>             if (a == 2) continue ext_loop;    // 3
>         }
>     }
> }
>
> would essentially be equivalent to :
>
> void f(int a)
> {
>     {
>         ext_loop_a :
>         int i = 0;
>
>         ext_loop_b :
>         for ( ; i < 10; ++i)
>         {
>             while (1)
>             {
>                 if (a == 0) goto ext_loop_c;    // 1
>                 if (a == 1) goto ext_loop_a;    // 2
>                 if (a == 2) goto ext_loop_b;    // 3
>             }
>         }
>         ext_loop_c:
>     }
> }
>
> I know, f will loop forever if a is 2...

"Mike Wynn" <mike.wynn@l8night.co.uk> wrote in message news:bi3ngf$1nn4$2@digitaldaemon.com...
> > > "Mike Wynn" <mike.wynn@l8night.co.uk> wrote in message news:bi1t45$227t$1@digitaldaemon.com...
> > > > to continue (a little) the old goto debate,
> > > > one of the uses of goto is to get to the end of a block from an if
> > without
> > > > writing a 1000 nexted if else's ........
> > > >
> > > > I'd like to be able to write
> > > >     done:{
> > > >         ....
> > > >         if (...) {
> > > >             if ( ... ) { break done; }
> > > >         }
> > > >     }
> read the code .... `} while( false);`
> its only every run once, no infinite loop, its just a do..while loop to
> allow break to break from it
> instead of goto to the statement just after the loop end (break breaks
from
> loop it does not goto label)

I don't see what's so superior about the above versus this:

{
    ....
    if (...) {
        if ( ... ) { goto done; }
    }
}
done:


Yes, you can misuse goto.  But you can misuse the hell out named break if you tried to.  ;)   or HAD to.  8)

Sean

"Sean L. Palmer" <palmer.sean@verizon.net> wrote in message news:bi4io8$31ck$1@digitaldaemon.com...
>
> "Mike Wynn" <mike.wynn@l8night.co.uk> wrote in message news:bi3ngf$1nn4$2@digitaldaemon.com...
> > > > "Mike Wynn" <mike.wynn@l8night.co.uk> wrote in message news:bi1t45$227t$1@digitaldaemon.com...
> > > > > to continue (a little) the old goto debate,
> > > > > one of the uses of goto is to get to the end of a block from an if
> > > without
> > > > > writing a 1000 nexted if else's ........
> > > > >
> > > > > I'd like to be able to write
> > > > >     done:{
> > > > >         ....
> > > > >         if (...) {
> > > > >             if ( ... ) { break done; }
> > > > >         }
> > > > >     }
>
> I don't see what's so superior about the above versus this:
>
> {
>     ....
>     if (...) {
>         if ( ... ) { goto done; }
>     }
> }
> done:

not a great deal, only that 'goto' contains no implicit direction
break implied down the code and out the loop,
and when cutting and pasting, if you mode code outside the `done` loop you
get an error.

>
> Yes, you can misuse goto.  But you can misuse the hell out named break if you tried to.  ;)   or HAD to.  8)
but not in quite the same way, you can not break/continue from a loop you are not within.